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Monday, November 17, 2008

more gloomy weather in store for this week

I hate being the bearer of bad news but sunny and seasonably warm weather will continue into the weekend of the 22-23 November at least, as High pressure dominates the intermountain West. There is a broad (read weak) trough of Low pressure forming over the weekend, but for now it doesn't look like a snow producer for the Mesa. In fact the meager snowpack will suffer some melting this week as afternoon temperatures climb into the 40s on our ski trails.
Beyond the 7 day forecast, forecasters look to the state of the oceans for clues to future storm track and intensity. For the West, the Pacific holds some clues for this winter. By comparing two different oscillations: the El Nino Southern Oscillation (neutral this winter) and the Pacific Decadal Oscillation (cold this winter), I compared previous winters that were neutral ENSO/cool PDO for 5 sites in the Colorado mountains: Steamboat Springs, Winter Park, Crested Butte, Telluride, Silverton. Those years back to 1950 were:
2001-2002 (top 10 driest years for Colorado mtns) (followed by the summer of the Haymen, Coal Seam, and Missionary Ridge fires amongst many others) 
1978-1979 (top 10 snowiest years for CO mtns)
1953-1954 (top 10 driest years for CO mtns)
1951-1952 (top 10 snowiest years for CO mtns)

Initially you might think, as I did, that this is just noise or chaos to have two top 10 driest and two top 10 snowiest years occurring in this pattern. But this also indicates there is a tendency towards extreme winters under this Pacific pattern. Also by comparing these 10 years to the 30 year average (1971-2000), there is a tendency (just a tendency, not a guarantee by any means!) for a dry November, 
then a snowy December-January, followed by a dry February. So far that pattern is working out, so lets hope for the snowy Dec-Jan part to work out too! I will keep you posted when we get an inkling of Mesa snow. 
As gloomy as this weather is, we might as well try to enjoy the sunny and mild afternoons.  :~}

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